We propose to attempt to determine definitively whether human blood has measurable levels of cerebrosterol (24-hydroxycholesterol). Also whether liver, cerebrospinal fluid, and possibly other tissues have levels of cerebrosterol which can be measured using high-pressure liquid chromatography and gas chromatography-mass spectrometry methods. We also seek to determine the extent of uptake of cerebrosterol and other sterols in rat brain under certain experimental conditions, particularly by using cultures of cerebellum, spinal cord, etc., and radiolabeled sterols. We seek to determine whether cerebrosterol influences the uptake of cholesterol, cholesterol esters, etc., and the activity of certain tissue enzymes of CNS tissues in cell culture. BIBLIOGRAPHIC REFERENCES: "Cerebrosterol Metabolism in Rat Brain", Y.Y. Lin and L.L. Smith, Abstracts of Papers, 30th Southwest Regional Meeting, American Chemical Society, Houston, Tx., Dec. 9-11, 1974, Abstract No. 138. "Sterol Metabolism. XXXV. The Disposition of (24-H3) Cerebrosterol in Developing Rat Brain", Y.Y. Lin and L.L. Smith, J. Neurochem., 25, 659-665 (1975).